Air Apparent: Mapping air pollutants

Physicist, entrepreneur and father Mark Richards is concerned about the environment and, in particular, the air pollutants we expose our children to.

He wants people to know just how bad London air pollution is, so we think more carefully about our lifestyles and travel methods.

So he has developed a handy machine which can monitor air quality and help create a pollution map. And he has set up a company to sell it.

Mark takes us through the process of developing the air pollution measuring device; from a laboratory experiment to a commercial product.

His early research began by thinking how a beam of light travels through water and how it is affected by pollutants.

He then successfully transferred the model to light travelling through air, allowing him to monitor air pollutants.

The real challenge was to adapt the laboratory research for use in the real world. How could that bulky equipment be made into something portable?

“Just as you wouldn’t choose to drink a glass of dirty water, you wouldn’t choose to breathe in dirty air,” Mark explains. “With my physics, I’ve managed to develop something real, something useful and something that helps to improve the quality of life for my family by allowing them to see the air they breathe.

“Like most inventions, it starts off as a piece of research. I’m using this clean water to represent clean air. When I shine a beam of light through the water, it goes through fairly uninhibited.

“However, if there are pollutants present, that pollutant will absorb some of the light because when light hits a molecule, that molecule will absorb some of that light and transmit the rest. As a result, the beam gets weaker. I can use this principle to measure the amount of pollution in this water.

“If I was to conduct a similar experiment in the air, most air pollutants are not visible, they absorb very little visible light. Luckily, many air pollutants absorb light outside of the visible range: ultraviolet light.

“Instead of visible light, I can direct an ultraviolet light beam through the air. Any chemicals which are present will absorb specific wave lengths. Each pollutant has its own signature in the ultraviolet region.

“The resultant beam is measured with something called a spectrometer. I’ve aligned the optics, I’ve also connected the source and the spectrometer. Finally, I’ve run some air through the chamber and also injected some pollutants.”

Mark’s results show large peaks, which are due to sulphur dioxide, an important pollutant; it’s mainly produced by heavy industry and diesel engines. He also notes that the smaller peaks are due to nitric oxide, which is emitted by petrol engines.”

The experiment set up allows Mark to detect many different gases simultaneously. Not only that, he can actually measure how much of each gas is present.